I don't know why so many people have issues with this even after I have to explain how to solve it so many times. Although since it's proven to be such an issue, i'll post a tutorial on how to deal with it.

In your post region, you'll see 2 tabs, Editor and Source you WANT the Source tab to be selected before you even begin posting code into the box, if you start in 'Editor' mode, then switch over after you put code into the post box, it won't work. You need to have the 'Source' tab selected before you start posting code into your message.

I thought it was just a few people, but after you know why it happens, it's really an easy fix to remember. Might as well provide the guide/tutorial for those who still have yet to figure out the "secret". :)